This study examines the changes in uterine histamine content in mast-cell normal and deficient mice during deciduoma formation. Surgical trauma (e.g., sutures) and intraluminal injection of oil produce deciduoma formation in ovariectomized mast-cell normal (+/+) and mast-cell deficient (W/WV) pseudopregnant mice that had previously received a single control ovary transplanted under the kidney capsule. Mast-cell normal (+/+) mice exhibit significant elevation of total uterine histamine content during both trauma and oil induced deciduoma formation. Mast-cell deficient (W/WV) mice under conditions of similar deciduoma formation did not show any change in total uterine histamine content. These results indicate that the change in histamine observed in mast-cell normal mice during deciduoma formation is most likely of mast cell origin. The lack of any measurable change in uterine histamine in mast-cell deficient mice indicates that an increase of non-mast cell histamine is not a prerequisite for deciduoma formation.

The intraluminal injection of oil produced deciduoma formation in ovariectomized, mast cell-normal (+/+) and mast cell-deficient (W/Wv) mice that were treated with exogenous steroids. Oil injection and trauma (e.g. sutures) also produced a deciduoma in ovariectomized +/+ and W/Wv mice that had received a single control (+/+) ovary transplanted under the kidney capsule. After transfers of donor blastocysts, implantation and live births were obtained in +/+ and W/Wv mice containing a single ovary transplant. Our results demonstrate that uterine mast cells are not required for the production of a decidual cell response, implantation, gestation or the birth of live offspring in mice.

The ovaries from mast cell-normal (+/+) and mast cell-deficient (W/Wv) mice were examined with light and electron microscopy. In addition the effect of ovariectomy and subsequent steroid treatment on total uterine histamine content, total mast cell numbers and surface and glandular epithelial cell heights was measured. The ovaries of +/+ mice were normal, displaying various stages of follicular growth and atresia and numerous corpora lutea; the ovaries of W/Wv mice lacked follicles and corpora lutea but contained numerous hyperplastic interstitial cells which contained numerous lipid droplets, vesiculated mitochondria and abundant endoplasmic reticulum suggestive of steroid synthesis. Steroid treatment of ovariectomized +/+ and W/Wv mice caused a significant increase in uterine wet weight and endometrial surface and glandular epithelial cell heights. In +/+ mice, steroid treatment caused a concomitant increase in total mast cells per uterine horn while mast cells were totally absent in W/Wv mice. The increase in uterine histamine in +/+ mice is consistent with the increase in mast cell numbers. Measurable amounts of uterine histamine, which increases slightly after steroid treatment, were demonstrated in W/Wv mice. Since the uteri of +/+ and W/Wv mice respond to steroids in a similar manner with the sole exception being histamine content and mast cell numbers, our results demonstrate the potential of using these animals to investigate the role(s) of uterine mast cells and non-mast cell uterine histamine in the process of implantation and the formation of a decidual cell response.